Self-exciting alternator.



No. 808,555. PATENTBD DEC. 26, 1905.

' L. J. LB PONTOIS.

SELF EXCITING ALTERNATOR.

APPLICATION FILED r23. a. 1905.

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3:313 ig pl: I 41 m um M w- No. 808,555. I PATENTED DEC. 26, 1905. L. J. LE PONTOIS.

SELF EXCITING ALTERNATOR.

APPLICATION TILED FEB.3.1905.

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Wiimwoeo gvwc-nfoz @Ehgf 614; 514213 wi 7Z w No. 808,555. PATENTED DEC. 26, 1905. L. J. LB PONTOIS.

SELF EXCITING ALTERNATOR.

APPLICATION FILED FEB.3,1905

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t z em fimi g 32n cam W43 No. 808,555 PATENTBD DEC. 26, 1905. L. J. LB PONTOIS.

SELF EXCITING ALTERNATOR.

APPLICATION FILED FEB. 3. 1905,

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lmtmwoeo n PATENTED DEC. 26, 1905.

J; LE PONTOIS. sELE EXCITING ALTERNATOR.

APPLICATION FILED YEB. 3. 1905.

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UNITED STATES PATENT OFFICE.

LEON JULES LE PONTOIS, OF NEW ROCHELLE, NEW YORK, ASSIGNOR TO POLY-PHASE IGNITION SYSTEM COMPANY, A CORPORATION OF NEW YORK.

SELF-EXCITING ALTERNATOR.

Specification of Letters Patent.

Patented Dec. 26, 1905.

To (LZZ 111720177, it puny concern:

Be it known that I, LEON JULns Ln PON- TOIS, a citizen of the Republic of France, and a resident of New Rochelle, VVestchester county, New York, have invented certain new and useful Improvements in Self-Exciting Alternators, of which the following is a specification.

The present invention relates to a magnote-alternator especially designed for the generation of alternating-current waves havdemagnetization of the field-magnets occurring so frequently in alternating-current magnetos.

Generally speaking, the alternating-current generator I have devised belongs to the type known as inductor-alternators," in which type the moving element may be an iron inductor modifying by its rotation the intensity of the magnetic flux threading through stationary windings, whereby alternating currents are set up in said windings. The intensity of such currents depends evidently on the rate at which the intensity of the magnetic flux is modified by the rotation of the inductor, this depending in turn on the angular speed of the inductor and to a great extent on the shape of the inductor-teeth.

The object of the present invention is primarily to construct a generator adapted to deliver currents to spark coils periodically and during a very short time, and it therefore follows that the inductor-teeth can be so shaped that the intensity of the magnetic magnetic flux is increased by the rotation of the inductor at the same rate at which it is decreased, the succeeding values of the posi' tive and negative waves of the current generated will be without efiect on the permanent magnetic field, the magnetic action of one current being equal to the demagnetizing efiect of the other current. If, however, the rate of decrease of the magnetic flux is greater than the rate of increase, the resultant action of both current-waves on the magnetic field will be, according to the law of Lens, a magnetizing action. I am aware of the fact that a generator constructed so as to give such a current-wave could not be utilized in practice for lighting or power transmission; but for the purpose of the present invention it is highly eflicient, as it gives a current-wave best suited for the operation of so-called spark-coils, while at the same time its permanent magnetic field does not lose its magnetism.

I have described in the present specification a generator adapted to be driven by an internal-combustion engine and constructed so as to furnish to said engine through the intermediary of a sparkcoil periodically and at the proper time sparks having suflicient intensity for its effective operation, and I have described in connection therewith a system for the proper distribution and utilization of the current in a multiple-cylinder internal combustion engine. In the construction of the generator I employ a fieldmagnet made in accordance with my application, Serial No. 229,310, filed October 20, 1904.

The circuit-breaker which is combined with the inductor-alternator is mounted infiXed relation to the stator in order to secure at all times coincidence between the period of maximum intensity of the current and the time of breaking of the circuit to obtain in the transformer a high-tension spark suitable for ignition purposes. To secure such coincidence, the breaker is operated positively and automatically by a cam on the inductor so placed as to break the circuit at or near the time when the alternating current generated reaches its maximum intensity. By se-- curing and maintaining the stator and breaker in fired relation to each other it follows that whatever be the angular position of the rotor relative to the stator the time of operation of the breaker will always coincide with the time when the current reaches its maximum intensity. As a change in the time of sparking is required for the efficient working of internal-combustion engines running at variable speeds, I am enabled to obtain any range of sparking by simply shifting angularly the rotor and its attached cam on their common axis. It may be stated here that the function of the breaker is to short-circuit the alternating current on its own circuit at or near its maximum and to suddenly open the circuit, so as to throw the energy accumulated in the form of self-induction in the primary of an induction-coil shunted by a condenser of determined condensance, so that a large part of the energy of the current generated shall appear in the spark taking place across the terminals of the secondary of the induction-ooil. To prevent the oxidation or deterioration of the contact-points of the breaker due to inevitable arcing notwithstanding the presence of the condenser across the gap, Iinclose the breaker-terminals in a bath of nonvolatile liquid, preferably glycerin.

The high-tension-current distributor which I combine with the inductor-alternator and the breaker in a unitary structure is designed to distributehigh-tension currents from a single spark-coil successively to jump spark plugs of multiple-cylinder internal-combustion engines.

In the accompanying drawings, Figure 1 is a central vertical section of a unitary structure comprising the inductor-alternator, the breaker, and distributer. Fig. 2 is a vertical sectional view on the planes of the lines 2 2 of Fig. 1. Fig. 3 is an end view of the distributer with the cover removed. Fig. 4 is an end view of the breaker. Fig. 5 is a crosssectional view at right angles to Fig. 1. Fig. 6 is a diagrammatic view of the connections between the generator, breaker, transformer, distributer, and spark-plug; and Fig. 7 is a diagrammatic view representing the shape of the peculiar alternatingcurrent wave gener ated by the alternator.

Similar reference characters indicate similar parts in the several views.

The system herein described is applicable to any well-known form of jump-spark ignition, and while I have shown a structure adapted to a four-cycle four-cylinder engine it may be applied to an engine having any number of cylinders.

In order to secure a unitary structure combining the inductor-alternator, breaker, and distributer, I provide an inclosing and supporting casing formed of a wall 1 of substantial circular section, having end covers 3 and 41 secured thereto by suitable means. These parts are preferably castings of any desired non-magnetic material, they having in practice been made of aluminium on account of its lightness. Secured to the wall 1 are studs 13, by which the entire structure may be attached to a base. Extending centrally through the casing is a shaft 5, supported in the bearings 2 and 2, the former constituting part of a web integral with the wall 1 and the latter formed integral with the end cover 4. As the construction shown is applied to a four-cycle four-cydinder engine, the shaft 5 is driven by suitable connections at the same speed as the engine-shaft. Keyed on the shaft 5 is the inductor-armature 6, having polar projections 7, constructed as hereinafter described and adapted to be rotated by said shaft between and in close proximity to the pole-pieces of an annular permanent magnet. This magnet is formed of a steel ribbon 8, continuously wound in the form of a helix after it has been hardened. Instead of winding in a circular or ring form the steel ribbon may be wound in the form of an oval, a rectangle, or square, suitable insulating material being interposed between adjacent con volutions. After the steel ring has been Wound and the ends securely fastened it is accurately ground on both faces and placed in a powerful magnetic circuit, closing itself by each side of the magnet to thereby develop in two opposite zones-two opposite magnetic poles. An annular segment 9 of annealed wrought-iron constituting a polar projection is slipped over and fastened to the ring 8 at one of its zones, special care being taken that said segment fits perfectly over the whole surface of the zone in order to reduce the reluctance of the magnetic oint to a minimum. [00

An annular segment 10, also made of annealed wrought-iron, is slipped over and fastened to the other zone, the zone-surface covered by the segment 10 being equal to the surface covered by the segment 9. It can thus be seen that the magnetic field concentrated about the poles 9 and 10 closes itself throughout space from pole 9 to pole 10. Two coils 1.1 and 12, respectively, are Wound on the polar projections 9 and 10. The polar projections 9 and 10 aresecurely fastened to the wall 1 by suitable means. As theinductor-armature 6 is rotated it will cause variations in the intensity of the magnetic flux threading through the coils 1]. and 12, and these coils will therefore become the seats of periodic alternating currents. It has been found preferable .to connect the coils 11 and 12 in parallel, grounding one terminal of their convolutions in order to secure a better insulation for their combined circuits. Although it would be feasible to use a single coil, I prefer to use two coils in order to equalize the magnetic pull exerted by the poles of the inductor, as the pull exerted individually by each pole is modified by the current flowing through the coils surrounding it. In

Fig. 6 the circuit is diagrammatically shown. One terminal of the coils 11 and 12 is connected to the primary 55 of an mductioncoil, the terminal of said primary being grounded in mass. The secondary 56 of the induction-coil is grounded in mass, the other terminal being connected to the distributerarm 40. A condenser having a condensance equal to the reactance of the primary is connected to one terminal of the primary and to ground. The breaker hereinafter described is connected across the terminals of the primary of the induction-coils.

In order to prevent the alternating cur rents generated exerting a demagnetizing action on the magnetic held, I make the armature 6 dissymmetric in the following manner: As the current utilized for ignition purposes is that one induced in the coils when the reluctance of the magnetic circuit increases suddenly, the faces 62 of the polar projections 7 are made sharp and extend radially from the hub of the armature, so' that the reluctance of the magnetic field threading through the coils 11 and 12 will increase suddenly as the armature is rotated in the direction of the arrow, Fig. 2. The curve representing the alternating current produced when the faces 62 leave the pole-pieces 9 and 10 will be very abrupt, as shown in Fig. 7. The faces 63 of the polar projections 7, however, are rounded and formed at a more obtuse or greater angle with the hub of the armature than that formed by the faces 62, so that the current induced in coils 11 and 12 when the reluctance of the magnetic field tends to decrease by reason of the pole pieces 7 approaching coincidence with the poles 9 and 10 is not of as great value as.

when the pole-pieces 7 leave the polar proj ections of the field.

The curve a of Fig. 7 shows the form of the current-wave generated by the alternator when the intensity of the magnetic field threading through the armaturecoils decreases by reason of the armature approaching the polar projections of the field, and the curve I) shows the form of the current-wave generated in the coils when the magnetic intensity of the field threading through the coils tends to decrease, owing to the inductor leaving the pole-pieces. It will be noticed that curve a is flattened because of the very progressive increase in intensity of the magnetic field, owing to the shape of the inductor, while the curve I) is, on the contrary, very abrupt and rises to a higher peak, owing to the form of the other face of the inductor, which causes the intensity of the magnetic field to decrease very rapidly. Owing to the pres ence of the condenser 57 in parallel with primary 55 of the induction-coil, the demagnetizing-current is in phase with its electromotive force, and therefore the demagnetizing action is slight, not only because the armature is shaped to make the demagnetizingcurrent curve of less value, but because this current takes place before the armature offers a good magnetic circuit for the demagnetizing magnetomotive force.

The breaker employed by me in the utilization of the current generated by the inductoralternator before described is inclosed within a casing 15, forming an integral part of cover 4, a cover 16 being secured to the casing by bolts. The cover 4, as shown in Fig. 5, is formed with an extension 14 to accommodate coils 11 and 12. Secured to shaft 5 by set-screws is a cam 17, having two cam-surfaces 1S and 19 diametrically opposite each other, said surfaces being adapted to effect a sudden break in the circuit through the following means.

20 designates an arm pivoted at 21 on a stud of cover 4, and said arm encircles the cam 17 for one hundred and eighty degrees and carries at its lower end a platinum terminal 22 and at the other a case-hardened steel head 23.

Screw-threaded into the lower part of cats ing 15 is a bushing 24, of insulating material, and supported in said bushing is a brass plug 25, of suflicient length to extend into the chamber of casing 15. The plug 25 is formed at its upper end with a terminal 26 and at its lower projecting end is provided with a binding-post to receive the low-tension wire 27. Fastened to hub 28 of cover 4 is a coiled spring 29, the free end of which presses firmly on terminal 22 to insure good contact with the other terminal 26. The chamber inclosing the breaker-terminals 22 and 26 is filled with a non-volatile liquid, preferably glycerin, to prevent oxidation and consequent burning of the terminals. The glycerin-bath prevents the formation of an are which would be practically a continuation of the short circuit and deprives the primary circuit of the induction-coil of a large amount of energy of self-induction stored in the generator-coils during their short circuit, which energy should be wholly delivered to the primary circuit of the induction-coil.

The terminals 22 and 26, as above stated, are held normally in contact with each other by spring 29. When cam 17 is rotated, shoulders at the ends of faces 18 and 19 of said cam will contact with the head 23, thereby rocking arm 20 upward and causing a sudden break in the circuit by separating the terminals 22 and 26, such break occurring twice for each revolution of the inductor. A stop-pin 30, secured to hub 28, serves to limit the upward movement of arm 20. The cam 17 is so positioned as to cause the break in the short-circuited armature-current circuit at or near the time when the current is at its maximum intensity and to remain broken until the demagnetizing-current reaches its minimum value. As a cam-face wipes from under the head 23 the arm 20 will be moved by spring 29 to close the circuit through the terminals 22 and 26. This closing of the circuit takes place at a definite time. known that in generators of this class the alternating current has a magnetizing and de' equal and the density of the magnetic field,

if it be a permanent field, is practically unaltered. Taking advantage of these facts I utilize for the operation of the induction-coil, the current-wave obtained at the time when the inductor leaves the polar projections of the field which, according to the law of Lenz, tends to oppose the decrease in the magnetic flux threading through the generator-coils.

The demagnetizing action on the field by the other current-wave generated when the inductor approaches or covers the polar projections is, however,very slight, owing to the fact that the generating-coils 1] and 12 are in series with the primary 55 of the inductioncoil and that the combined reactance and resistance of the circuit is sufficient to 'nevent the current from reaching a harmful value. It can thus be seen that the action of the alternating current on the density of the magnetic field-that is, on the life of the magnet-tends to maintain the magnetic field in its normal degree of permanent magnetization. I have observed that under such conditions the permanent magnetic field becomes strengthened. I therefore make the lengthof the raised surfaces of the faces 17 and 18 sufficient to maintain the armaturecoils in series with the prin'iary of the induction-coil while the demagnetizing current- Wave occurs, their circuit being short-circuited on itself while the magnetizing wave occurs.

Inasmuch as the stator and the breaker are rigidly secured to the casing, they will always maintain a fixed relation to each other whatever may be the position of the rotor relatively to the stator. Thc rotor and cam 17 always maintain the same positions relatively to each other; but their positions relative to the stator and breaker, respectively, may be varied at will either automatically or by hand. This feature of adjustment of the rotor and cam, while maintaining the same relative positions to each other, affords a means for always interrupting the circuit at a time when the current is at or near its maximum intensity. The rotor and its attached cam may be angularly adjusted by any suitable means, a simple and efficient expedient being shown in the drawings consisting of a plunger 44, supported by and adapted to be moved longitudinally in the hollow end of shaft 5. The plunger 44 has secured thereto a pin 45, engaging the walls of a cam-slot 46 in said end of shaft 5. it is obvious that as the plunger is moved back- It is well ward and forward the rotor will be angularly shifted on its axis in one direction or the other relative to the stator. Also cam 17 will be shifted angularly with the rotor, so as to enable at all times the breaking of the current at or near the period of its maximum intensity.

The third elem ent of the unitary structure is the distributor for the high-tension current. The distributor is constructed and op erated as follows: On the end of shaft is keyed a spur-gear 31, meshing with a similar gear 32, the shaft 33 of the latter having a bearing in. a journal supported by web 47, formed integral with the wall 1 The diameter of the gear 32 is twice that of gear 3]., so that the former will make one revolution to two of the latter. Secured to the side of gear is a ring 34, of insulating material, having a central boss 35, projecting through an opening in an annular disk 36, of insulating material, said disk being secured by screws to the wall 1 of the casing. Secured on the boss 35 is a sleeve 37, having a shoulder bearing against a plate or ring 38, secured by suitable means to the disk 36, said sleeve and ring being made of conductive material, preferably brass. A spring P9, surrounding the boss 35, insures good contact between sleeve 37 and. ring 38. The moving element of the distributor consists of an arm 40, secured to sleeve 37, said arm czn'rying at its outer end a comb 1-1 having a plurality of sharp needles thereon to permit the formation of numerous brush dischar es. The disk 36 has secured to its face by screws four polar segments 42, the faces of which may be roughened or ctn'rugated, so as to present surfaces favorable to the production of silent brush discharges between them and the moving element of the distributor. ln order to prevent formation of direct brush discharges through space between contiguous segments, their edges facing each other are carefully rounded, as shown inv Fig. 3, and polished. Also by reference to the same figure it will be seen that a long non-conducting surface is placed between contiguous segments, so as to prevent undue formation of two or more sparks simultaneously in different cylinders. Said segments are also prevented from brush discharging with ring 38 by a circular wall 48, forming an integral part of the annular disk 3 The segments 12 are formed. with eyes at), adapted to receive terminals secured at the endsof four heavily-insulated wires 50, leading to different spark-plugs, the hightension wire 52 being connected to ring 38. The cover 5-3 has its inner face lined with a plate of mica 51 to prevent brush discharg ing through the cover.

justed that the comb 1; 1 as it rotates will pass within about one one-hundredth of an inch of the polar segments 42, it being preferred that there shall be at no time actual metal- The arm 40 is so adlic contact between the comb and the segments. Such adjustment reduces considerably the electrical resistance of the sparkgap and gives a result for the desired purpose as good as that obtained from actual contact. In the operation of the apparatus above described as the shaft 5 is rotated the arm 40 and comb 41 willbe carried thereby, so as to cause the latter to successively pass over the polar segments 42, which are in communication with the four spark-plugs 58, 59, 60, and 61 in the engine-cylinders, said arm 40 making one complete revolution to two revolutions of the shaft 5. One terminal of the secondary is grounded, as usual, the other terminal being connected through conductor 52 to the ring 38, the high-tension current passing from ring 38 through sleeve 37, arm 40, comb 41, where a silent brush discharge takes place between the teeth of said comb and the surfaces of the polar segments 42, the current then flowing by cables to the several spark-plugs located in the enginecylinders as the comb 41 passes over them successively and thence by the spark-gap of the spark-plug to ground, thus completing the circuit. The formation of brush discharges issuing from many points considerably reduces the resistance rising in the circuit by reason of the air-gap between the comb 41 and the polar segments 42. Also the nonformation of disruptive discharges tends to prolong the life of the comb, inasmuch as a very small amount of metal is electrolytically deposited from pole to pole.

The cover 4 is provided with a suitable oilhole 53, bywhich alubricant maybe supplied to one bearing of the shaft 5, the other bearing being supplied with the lubricant oiltube 54.

What I claim, and desire to secure by Letters Patent, is

1. A partially-self-exciting alternator of the inductor type, comprising a permanent magnetic field, polar projections adjacent to the magnetic poles developed bysaidfield, stationary windings surrounding said polar projections, and a dissymmetric inductor-rotor having such form that the waves of the alternating current generated which have a magnetizing effect on the permanent magnetic field reach a higher value than those which have a demagnetizing effect on said field.

, 2. A partially-self-exeiting alternator of the inductor type, comprising a permanent magnetic field, annealed polar projections adjacent to the poles of said magnet, statlonary ary windings surrounding the poles of said.

magnet, and a dissymmetric inductor-rotor for the purpose described.

4. A partially-self-exciting alternator of the inductor type, comprising a permanent field-magnet consisting of a magnetized ring formed of a continuous steel ribbon, polar projections adjacent to magnetic poles developed by said field, stationary windings surrounding said polar projections, and an inductor-rotor having polar projections, one face of said projections extending radially from the hub of the rotor, and the other face rounded and formed at an angle with the hub greater than that of the radial face whereby the waves of the alternating current generated which have a magnetizing effect on the permanent magnetic field reach a higher current value than those which have a demagnetizing effect on said field.

5. A partially-self-exciting alternator of the inductor type, comprising a permanent field-magnet consisting of a magnetized ring formed of a continuous steel ribbon, and an inductor-rotor having polar projections, one face of said projections extending radially from the hub of the rotor, and the other face rounded and formed at an angle with the hub greater than that of the radial facewhereby the waves of the alternating current generated which have a magnetizing effect on the permanent magnetic field reach a higher current value than those which have a demagnetizing effect on said field.

In testimony whereof I have hereunto signed my name in the presence of two subscribing witnesses.

LEON JULES LE PONTOIS.

Witnesses:

ALEXANDER S. RoDMAN, GRAoE L. I-IEAsLEY. 

